Results 4 issues of Pierre-Yves Strub

Quoting `finfun.v` documentation: > {ffun fT} inherits combinatorial structures of rT, i.e., eqType, choiceType, countType, and finType. However, due to some limitations of the Coq 8.9 unification code the structures...

kind: enhancement

Because it's fun.

enhancement :sparkles:
experiment :test_tube:
TODO: MC2 port

The notation [`x] badly interact with the [] selector and the notation for the norm.